System and method for medium access control in a power-save network

ABSTRACT

A method and apparatus for accessing, controlling and utilizing a network communication medium. Various aspects of the present invention may comprise a first networked device with power-save capability. The first networked device may acquire control of a communication medium utilizing a medium access protocol, which may be contention-based. The first networked device may utilize the communication medium to communicate information to a second networked device. The first networked device may transfer control of the communication medium to the second networked device, whereby the second networked device may control the communication medium without having to acquire control of the communication medium by utilizing the medium access protocol. The second networked device may utilize the communication medium to communicate information to the first networked device while maintaining control over the communication medium. The second networked device may have buffered such information for delayed delivery to the first networked device.

CROSS-REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY REFERENCE

This patent application claims the benefit of U.S. ProvisionalApplication No. 60/501,781, filed Sep. 10, 2003, titled “SYSTEM ANDMETHOD FOR POWER MANAGEMENT IN A WIRELESS NETWORK,” the contents ofwhich are hereby incorporated herein by reference in their entirety.

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[Not Applicable]

SEQUENCE LISTING

[Not Applicable]

MICROFICHE/COPYRIGHT REFERENCE

[Not Applicable]

FIELD OF THE INVENTION

The present invention relates generally to medium access control. Morespecifically, the present invention relates to method and apparatus foraccessing, controlling and utilizing a communication medium in anetwork.

BACKGROUND OF THE INVENTION

Modern communication networks include a vast array of device types. Suchdevice types may include, for example, wired and wireless devices, andstationary and portable devices. Some networked devices may haverelatively limitless electrical power supplies, for example thosedrawing electrical power from wall outlets. Conversely, some networkeddevices may have limited power supplies, for example those operating oninternal batteries.

Networked devices operating with limited power supplies may adoptoperating characteristics that are conducive to conserving their limitedsupplies of power. For example, some devices may have an operating mode,sometimes called a “sleep mode” or “power-save mode,” where the deviceshuts down or slows down many of its internal functions to conserveenergy. Such functions may include, for example, network communicationfunctionality. Such devices may, for example, periodically or on-commandexit the power-save mode and re-establish communications with othernetworked devices.

For example, a remote network device in power-save mode may exit thepower-save mode and establish communications with a communicationnetwork access point. Once such communications are established, theexemplary remote network device and network access point may exchangeinformation. For example, the remote device may transmit information tothe access point that is destined for another networked device, and theaccess point may transmit information to the remote device that theaccess point has buffered for the remote device while the remote devicewas in power-save mode and unable to communicate with the access point.

The process of communicating information between the exemplary remotedevice and network access point, and between devices in general,consumes energy. Communication networks are generally governed byvarious communication procedures and protocols that control variouscommunication functions. Such functions may include, for example, accessto the communication medium and message queuing. Such communicationprotocols and other governing rules of information transfer typicallyinclude aspects that are inefficient with regard to, for example, powerconsumption, information transfer speed, and bandwidth utilization.

Further limitations and disadvantages of conventional and traditionalapproaches will become apparent to one of skill in the art, throughcomparison of such systems with the present invention as set forth inthe remainder of the present application with reference to the drawings.

BRIEF SUMMARY OF THE INVENTION

Various aspects of the present invention provide a method and apparatusfor accessing, controlling and utilizing a network communication medium.Various aspects of the present invention may comprise a first networkeddevice with power-save capability. The first networked device may, forexample, communicate an indication to various other network devices thatthe first networked device is capable of operating in a power-save mode.

Various aspects of the present invention may comprise the firstnetworked device acquiring control of a network communication mediumutilizing a medium access protocol, which may, for example, be acontention-based medium access protocol. The first networked device may,for example, acquire control of the communication medium after exitingfrom a sleep state of a power-save mode. The first networked device mayutilize the communication medium to communicate information to a secondnetworked device.

Various aspects of the present invention may comprise the firstnetworked device transferring control of the communication medium to thesecond networked device, whereby the second networked device may controlthe communication medium without having to acquire control of thecommunication medium by utilizing the normal rules of the medium accessprotocol. The first networked device may, for example, transfer controlof the communication medium to the second networked device bycommunicating a hand-off indication to the second networked device. Sucha hand-off indication may comprise, for example, an indication that thesecond networked device may assume control over the communicationmedium. Following transfer of communication medium control to the secondnetworked device, the first networked device may receive informationfrom the second networked device, if the second networked device hassuch information to send. Following receipt of information from thesecond networked device, the first networked device may re-enter a sleepstate of a power-save mode.

Various aspects of the present invention may comprise the secondnetworked device assuming control of the communication medium followingreceipt of a medium control hand-off indication from the first networkeddevice. The second networked device may, for example, accept a mediumcontrol hand-off from some networked devices, such as power-savedevices, and not from other devices, such as non-power-save devices.

Various aspects of the present invention may comprise the secondnetworked device, having assumed control of the communication medium,utilizing the communication medium to communicate information to thefirst networked device while maintaining control over the communicationmedium. The second networked device may, for example, communicate suchinformation to the first networked device in a single data packet orstream of data packets. The second networked device may, for example,have buffered such information for delayed delivery to the firstnetworked device.

These and other advantages, aspects and novel features of the presentinvention, as well as details of illustrative aspects thereof, will bemore fully understood from the following description and drawings.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 shows a flow diagram of a method for controlling access to andutilizing a communication medium in accordance with various aspects ofthe present invention.

FIG. 2 shows a flow diagram of a method for controlling access to andutilizing a communication medium in accordance with various aspects ofthe present invention.

FIG. 3 illustrates a first exemplary message exchange between twonetworked devices in accordance with various aspects of the presentinvention.

FIG. 4 illustrates a second exemplary message exchange between twonetworked devices in accordance with various aspects of the presentinvention.

FIG. 5 shows a block diagram of a system for controlling access to andutilizing a communication medium in accordance with various aspects ofthe present invention.

FIG. 6 shows a flow diagram of a method for controlling access to acommunication medium in accordance with various aspects of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a flow diagram of a method 100 for controlling access toand utilizing a communication medium in accordance with various aspectsof the present invention. For example and without limitation, the method100 may be implemented in a first device (e.g., a remote device withpower-save capability) in a communication network. For the followingdiscussion regarding FIG. 1, a device implementing the method 100 may bereferred to generally as the “first device.”

The method 100 includes, at step 110, waiting for an event to exit asleep state of a power-save mode. Such an event may include, forexample, a direct command from a user that requires a networked deviceoperating in the sleep state of the power-save mode to exit the sleepstate of the power-save mode. Such an event may include, for example,periodic expiration of a timer. Such an event may, in general, includeany event that would cause a device to at least temporarily exit thesleep state of the power-save mode.

The method 100 then includes, at step 120, the first device exiting thepower-save mode. The exemplary method 100 illustrated in FIG. 1incorporates aspects associated with a networked device havingpower-save capability, because the power-save environment is aconvenient environment in which to present some of the various aspectsof the present invention. Accordingly, the scope of various aspects ofthe present invention should not be limited to characteristics ofdevices having power-save capabilities or a network having devices withpower-save capabilities.

The method 100, at step 130, includes the first device acquiring accessto and control of the network communication medium. Such access andcontrol may include, for example, access and control of a singlecommunication channel, such as, for example, a FDM frequency, a TDMAtimeslot, a frequency hopping sequence, or a CDMA code. Such access andcontrol may include, for example, access and control of a plurality ofsuch communication channels. Such access and control may include, forexample, access and control of all communication channels in acommunication medium.

Such acquisition may include, for example, utilizing a contention-basedmedium access protocol to obtain access and control of at least aportion of a shared communication medium. For example, the first devicemay operate according to a carrier sense multiple access with collisionavoidance (CSMA/CA) protocol to obtain control of the networkcommunication medium. The first device may, for example in a wirednetwork, obtain access to the communication medium utilizing a carriersense multiple access with collision detection (CSMA/CD) protocol.Accordingly, the scope of various aspects of the present inventionshould not be limited to characteristics of a particular protocol orsuite of protocols. Similarly, the scope of various aspects of thepresent invention should not be limited to characteristics of aparticular communication medium or group thereof.

The method 100, at step 140, includes the first device utilizing thecommunication medium to communicate information to a second networkeddevice. A first device that has no information to communicate to asecond networked device may skip step 140. Such information may include,for example, data or control information. Such information may beincluded in a single data packet or plurality of data packets. Suchinformation may include, for example, unicast, multicast or broadcastinformation. The information communication may or may not include packetacknowledgement indications from the receiver of the communicatedinformation. Accordingly, the scope of various aspects of the presentinvention should not be limited to characteristics of particularinformation format or type. Nor should the scope of various aspects ofthe present invention be limited to characteristics of a particularcommunication mechanism.

Note that step 140 may include utilizing typical medium accesssafeguards, such as time limits, to maintain communication discipline inthe communication network. For example, step 140 need not enable thefirst device to control the communication medium in an uninterruptedfashion until the device has no more information to communicate. Suchunchecked control could, in particular scenarios, have detrimentaleffects on the communication network. Accordingly, for example, thenetwork may place constraints on the duration for which a device orgroup of devices may maintain control over the communication medium orportions thereof.

The method 100, at step 150, includes the first device passing controlof the communication medium to a second networked device. Havingreceived such medium control from the first device, the second devicemay then utilize the communication medium for communicating informationtraffic without having to perform various medium access activities, suchas, for example, contending with other networked devices for access tothe communication medium. For example and without limitation, if thefirst device communicates information at step 140 to a second device(e.g., a network access point), the first device may, at step 150, passcontrol of the communication medium to the second device or to someother networked device.

The first device may pass control of the communication medium to asecond device in a variety of ways. For example, the first device maycommunicate an explicit notification to the second device indicatingthat the second device may assume control over the communication medium.Alternatively, such a notification may be incorporated into a packetthat the first device communicates to the second device or anothernetworked device. Such a packet may also include, for example, controlinformation and/or data information. Accordingly, the scope of variousaspects of the present invention should not be limited tocharacteristics of a particular mechanism of passing control of thecommunication medium.

In an exemplary power-save environment, a remote power-save device maynotify a network controlling entity or access point that the power-savedevice has power-save capability. Then, upon the power-save devicesending a packet to the access point indicating that the power-savedevice has no data or no more data to send, the access point mayautomatically assume control of the communication medium for sendingdownstream traffic to the power-save device.

The access point may, for example, distinguish between power-savedevices and non-power-save devices in its network and interact with eachtype of device in a different manner. For example, the exemplary accesspoint may choose not to accept control from the remote device if theaccess point determines that the remote device does not have power-savecapability.

The method 100, at step 160, includes receiving information from thesecond device, which received control of the communication medium atstep 150. Of course, in a scenario where the second device has noinformation to communicate, step 160 may be skipped. Such information isnot to be limited to a particular type of data or data format. Forexample, such information may take the form of several discrete packetsof information, which include data and/or control information. Thesecond device may, for example, communicate one or more discrete packetsto the first device while maintaining control of the communicationmedium.

As mentioned previously with regard to communications from the firstdevice, the network may utilize various mechanisms to ensure that thesecond device does not retain control of the communication medium for anunduly long period. For example and without limitation, in acommunication system that places an upper limit on the time that aparticular device may control the communication medium, such acommunication system incorporating medium access control in accordancewith various aspects of the present invention may place such a limit onthe combined time for which the first and second devices may control thecommunication medium.

In an exemplary power-save network environment, the second device may bea network access point that has buffered traffic destined for thepower-save device while the power-save device was in a sleep state of apower-save mode. In general, the second device may include any networkedentity that has traffic to deliver to the first device. In acommunication scenario where the second device has no information tocommunicate to the first device, the method 100 flow may by-pass step160. Note that the scope of various aspects of the present inventionshould not be limited to receiving a particular type of information orreceiving information from a particular type of network entity.

The method 100, at step 170, includes notifying a user of recentlytransferred information. For example, a remote device may notify theuser of the remote device that the remote device has recently receivedupdated information from the network. The user may, for example, controlthe existence, nature and timing of such a notification. For example,the user may specify that the device is not to notify the user.Alternatively, for example, the user may specify that the device is onlyto notify the user of updates regarding particular types of information.Accordingly, the scope of various aspects of the present invention isnot to be limited to the existence of such a notification or the natureof any notification provided.

The method 100, at step 180, includes the first device re-entering thesleep state of the power-save mode. In the exemplary power-saveenvironment, having exchanged information with the network access point,the first device may re-enter the sleep state of the power-save mode.The method 100 flow may then return to method step 110, where the firstdevice again waits for an event to cause the first device to exit thesleep state of the power-save mode. As mentioned earlier, the power-savenetwork environment is for illustrative purposes and should not limitthe scope of various aspects of the present invention to characteristicsof power-save devices or networks including such devices.

FIG. 2 shows a flow diagram of a method 200 for controlling access toand utilizing a communication medium in accordance with various aspectsof the present invention. For the following discussion regarding FIG. 2,a device implementing the method 200 may be referred to generally as the“first device.” The first device may include, for example and withoutlimitation, an access point device in a communication network. For thefollowing discussion, a device implementing the method 200 may bereferred to generally as the “first device.”

The method 200, at step 210, includes receiving information from asecond device. The second device may have acquired access to thecommunication medium by performing steps of a medium access protocol(e.g., a contention-based medium access protocol). Step 210 includesvarious sub-steps, which may or may not be followed by the first devicedepending on the particular communication scenario. Step 210 may includeat step 212, for example, receiving an initial packet from the seconddevice. Step 210 may also include at step 214, for example, receivingadditional information packets from the second device.

In one exemplary scenario, the first device may perform step 214 whenthe second device has more information to communicate to the firstdevice than can reasonably be packaged in a single packet. System packetsize constraints may also limit packet size. Step 210 may furtherinclude at step 216, for example, receiving an indication from thesecond device that the first device may assume control of thecommunication medium. Such an indication may be an explicit directive ormay, for example, be an indication that the second device has no data orno more data to send to the first device.

The various information-receiving steps discussed previously areexemplary and should not limit the scope of various aspects of thepresent invention. For example, the initial packet communicated at step212 may be the only packet communicated to the first device. Thatinitial packet may, for example, include data information, controlinformation, and the indication that the first device is to take controlof the communication medium. Accordingly, the scope of various aspectsof the present invention should not be limited to a particular packet ormessage format or packet stream format.

The exemplary method 200, as will be discussed below, is shown acceptingcontrol of the communication medium from network devices havingpower-save capability and not from network devices that to not havepower-save capability. It should be noted that various aspects of thepresent invention should not be limited to various characteristics ofthis exemplary model. For example, various aspects of the presentinvention apply equally well to networked devices that have and do nothave power-save capability.

The exemplary method 200, at step 220, includes determining if thesecond device is a power-save device. Such a determination may be madein a variety of ways. For example, the second device may have previouslyregistered with the network as having power-save capability and may belisted in a database as having such capability. Also, for example, thesecond device may incorporate indications of its power-save capabilityin various messages sent by the second device to the first device.Accordingly, the scope of various aspects of the present invention shallnot be limited by a particular method of indicating power-savecapability or a particular method of determining whether a networkeddevice has power-save capability.

If the second device is not a power-save device, the exemplary method200 flow continues at step 250, which will be discussed below. If thesecond device is a device having power-save capability, the method 200flow continues at step 230.

The method 200, at step 230, includes determining whether there istraffic waiting to be communicated to the second device. For example,the first device, which may for example be a network access point, mayhave stored message traffic destined for the second device in a buffer.The first device may have performed such storage, for example, if thesecond device is a registered power-save device. If there is no trafficto be sent to the second device, the exemplary method 200 flow continuesat step 250, which will be discussed below. If there is traffic to becommunicated to the second device, the method 200 flow continues at step240.

The method 200, at step 240, includes communicating information trafficto the second device. Step 240 includes various sub-steps, asillustrated in FIG. 2, that may or may not be followed depending on theparticular communication scenario. The method 200, at step 242, includesaccepting control of the communication medium that was passed from thesecond device at step 216. By accepting control of the communicationmedium passed from the second device, the first device may by-passhaving to perform various medium access acquisition tasks, such as, forexample, contending with other network devices for access to thecommunication medium. For example and without limitation, if thecommunication medium is generally governed by a contention-based mediumaccess protocol, the first device may immediately begin communicatinginformation back to the second device instead of having to queue theinformation and contend for access to the communication medium for eachinformation packet to be sent to the second device.

As discussed previously, the exemplary method 200 does not accept acommunication medium control hand-off from a non-power-save device.However, as also discussed previously, the scope of various aspects ofthe present invention should not be limited to only accepting mediumcontrol hand-off from power-save devices.

The method 200, at step 247, includes retrieving information trafficdestined for the second device that may have been stored in a buffer.Such information retrieval may have latency that does not provide formeeting the message timing requirements of the system. Accordingly, theexemplary method 200 includes an exemplary mechanism at steps 244 and246 by which control of the communication medium may be maintained andthe second device may be notified that information is coming in spite ofsuch latency. The method 200, at step 244, determines whether theinformation retrieval latency is too great to meet the communicationmedium protocol's messaging timing requirements. If step 244 determinesthat the buffered information will not be retrieved in time to meet thecommunication medium protocol's messaging requirements, method 200 flowcontinues to step 246. Step 246, in turn, includes communicating amessage over the communication medium to the second device thatindicates information will eventually follow. The mechanism discussedabove to compensate for information retrieval latency is exemplary. Themethod 200 may employ a variety of alternative mechanisms to handle suchlatency. Accordingly, the scope of various aspects of the presentinvention should not be limited to characteristics of a particularlatency handling mechanism.

When the first device has retrieved information destined for the seconddevice, at step 247, and the first device is ready to communicateretrieved information to the second device, the method 200, at step 248,communicates the retrieved information to the second device. The firstdevice may, for example, communicate the information over thecommunication medium while maintaining control of the communicationmedium. Step 248 may, for example, communicate the information to thesecond device in one packet or a plurality of packets. Accordingly, thescope of various aspects of the present invention should not be limitedto a particular message or packet format or packet stream format.

After the first device has communicated the information to the seconddevice at step 248, the method 200, at step 250, releases control of thecommunication medium. Such release may include, for example,communicating an explicit release message or may include, for example,remaining silent for a predetermined period of time in accordance withthe rules of medium access for the particular communication medium inuse. Accordingly, the scope of various aspects of the present inventionshould not be limited to a particular medium control release mechanism.

As discussed previously, the communications between the first and seconddevices may be subjected to various communication network safeguards,such as time constraints, to ensure that other networked devices havefair access to the communication medium.

FIG. 3 illustrates a first exemplary message exchange 300 between twonetworked devices in accordance with various aspects of the presentinvention. The exemplary message exchange 300 is provided in the contextof the IEEE 802.11 standard. However, by no means, should the scope ofvarious aspects of the present invention be limited to IEEE 802.11features and implementations.

The top row of the message exchange 300 is labeled “QSTA.” Thisgenerally refers to a quality of service station in the IEEE 802.11context. The QSTA may be generally thought of, for this example, as afirst networked device that may have power-save capabilities. The bottomrow of the message exchange 300 is labeled “QAP.” This generally refersto a quality of service access point in the IEEE 802.11 context. The QAPmay be generally thought of, for this example, as a second networkeddevice.

Prior to the exemplary message exchange 300, the QSTA gains access toand control of the communication medium. For example, the QSTA mayacquire access to the communication medium following a contention-basedmedium access protocol, such as CSMA/CA.

The message (or packet) exchange 300 begins with a first message 310sent from the QSTA to the QAP. The first message 310 may, for example,be a Q-Data message with the More flag set. Such an exemplary firstmessage 310 may communicate data to the QAP and also indicate to theQAP, in a power-save scenario, that the QSTA is not currently in a sleepstate of a power-save mode.

Following an inter-frame spacing interval (SIFS), the message exchange300 includes the QAP sending a second message 320 to the QSTA. Thesecond message 320 may, for example, be an acknowledgement message (ACK)to indicate to the QSTA that the QAP successfully received the firstmessage 310.

The message exchange 300 then includes a third message 330 from the QSTAto the QAP. The third message 330 may, for example, be a Q-Data messagewith the More flag unset. The unset More flag may indicate to the QAPthat the QSTA has no more data to send to the QAP. The unset More flagmay also, for example, indicate a handoff of control of thecommunication medium from the QSTA to the QAP.

As discussed previously, the QAP, at this point, may treat power-savedevices differently than non-power-save devices. For example, if the QAPdetermines that the QSTA is not a power-save device, the QAP may merelyacknowledge receipt of the third message 330 and cease communicatingwith the QSTA, thereby releasing the communication medium. Conversely,if the QAP determines that the QSTA is a power-save device, the QAP mayaccept control of the communication medium from the QSTA, for example,for the communication of information traffic back to the QSTA.

At this point in the exemplary message exchange 300, the QAP assumescontrol over the communication medium. The QAP responds by sending afourth message 340 to the QSTA. The fourth message 340 may, for example,be a Q-Data message that includes data for the QSTA and an indicationacknowledging receipt of the third message 330.

The exemplary message exchange 300 then includes a fifth message 350from the QSTA to the QAP, which may, for example, acknowledge receipt ofthe fourth message 340. The message exchange 300 then includes a sixthmessage 360 from the QAP to the QSTA, which may, for example, includeadditional data for the QSTA. The message exchange 300 then includes aseventh message 370 from the QSTA to the QAP, which may, for example,include an indication acknowledging receipt of the sixth message 360.

The exemplary message exchange 300 may continue with the QSTA and theQAP exchanging information, for example, until the QAP exhausts itssupply of information to be communicated to the QSTA. Alternatively, forexample, the QSTA and QAP may discontinue the message exchange 300 dueto expiration of a medium access time limit or other medium accesscontrol mechanism, or due to other considerations regarding fairness ofaccess or attempts to guarantee good quality of service to thecollection of QSTA within the network.

FIG. 4 illustrates a second exemplary message exchange 400 between twonetworked devices in accordance with various aspects of the presentinvention. As with the exemplary message exchange 300 illustrated inFIG. 3, the second exemplary message exchange 400 is provided in thecontext of the IEEE 802.11 standard. However, by no means, should thescope of various aspects of the present invention be limited to IEEE802.11 features and implementations.

The top row of the message exchange 400 is labeled “QSTA.” Thisgenerally refers to a quality of service station in the IEEE 802.11context. The QSTA may be generally thought of, for this example, as afirst networked device that may have power-save capabilities. The bottomrow of the message exchange 400 is labeled “QAP.” This generally refersto a quality of service access point in the IEEE 802.11 context. The QAPmay be generally thought of, for this example, as a second networkeddevice.

Prior to the exemplary message exchange 400, the QSTA gains access toand control of the communication medium. For example, the QSTA mayacquire access to the communication medium following a contention-basedmedium access protocol, such as CSMA/CA.

The message (or packet) exchange 400 begins with a first message 410sent from the QSTA to the QAP. The first message 410 may, for example,be a Q-Data message with the More flag unset. Such a first message 410may, for example, indicate to the QAP in a power-save scenario that theQSTA is not currently operating in a sleep state of a power-save modeand is standing by to receive traffic that the QAP may have beenbuffering for the QSTA while the QSTA was in a sleep state of apower-save mode. The unset More flag may also indicate a handoff ofcontrol of the communication medium from the QSTA to the QAP.

As discussed previously, the QAP, at this point, may treat power-savedevices differently than non-power-save devices. For example, if the QAPdetermines that the QSTA is not a power-save device, the QAP may merelyacknowledge receipt of the first message 410 and cease communicatingwith the QSTA, thereby releasing the communication medium. Conversely,if the QAP determines that the QSTA is a power-save device, the QAP mayaccept control of the communication medium from the QSTA for thecommunication of information traffic, for example, from the QAP to theQSTA.

At this point in the exemplary message exchange 400, the QAP assumescontrol over the communication medium. Following an inter-frame spacinginterval (SIFS), the message exchange 400 includes the QAP sending asecond message 420 to the QSTA. The second message 420 may, for example,include an acknowledgement indication (ACK) to indicate to the QSTA thatthe QAP successfully received the first message 410.

Additionally, for example, the second message 420 may include a nulldata frame, which may indicate to the QSTA that the QAP has informationtraffic buffered for delivery to the QSTA, but that the QAP needsadditional time to acquire the information from the buffer. Such a nulldata frame may, for example, allow the QAP to retain control of thecommunication medium (e.g., a communication medium controlled by acontention-based medium access control protocol) while the QAP isobtaining the information traffic destined for the QSTA.

The exemplary message exchange 400 then includes a third message 430from the QSTA to the QAP. The third message 430 may, for example,include an indication to acknowledge receipt of the second message 420by the QSTA.

The message exchange 400 then includes a fourth message 440 from the QAPto the QSTA, which may, for example, include information for the QSTAthat the QAP retrieved from a buffer. The message exchange 400 thenincludes a fifth message 450 from the QSTA to the QAP, which may, forexample, include an indication acknowledging receipt of the fourthmessage 440.

The message exchange 400 then includes a sixth message 460 from the QAPto the QSTA, which may, for example, include additional information forthe QSTA that the QAP retrieved from a buffer. The message exchange 400then includes a seventh message 470 from the QSTA to the QAP, which may,for example, include an indication acknowledging receipt of the sixthmessage 460.

The exemplary message exchange 400 may continue with the QSTA and theQAP exchanging information, for example, until the QAP exhausts itssupply of information to be communicated to the QSTA. Alternatively, forexample, the QSTA and QAP may discontinue the message exchange 400 dueto expiration of a medium access time limit or due to some other form ofmedium access control mechanism, or due to other considerationsregarding fairness of access or attempts to guarantee good quality ofservice to the collection of QSTA within the network.

FIG. 5 shows a block diagram of a system 500 for controlling access toand utilizing a communication medium in accordance with various aspectsof the present invention. The system 500 includes a first communicationmodule 510, which may, for example, be utilized by a first networkeddevice. Various components of the first communication module 510 may,for example, perform various aspects of the method 100 illustrated inFIG. 1. The system 500 also includes a second communication module 540,which may, for example, be utilized by a second networked device.Various components of the second communication module 540 may, forexample, perform various aspects of the method 200 illustrated in FIG.2. For the following discussion regarding FIG. 5, a network deviceutilizing the first communication module 510 may be referred to as the“first device,” and a device utilizing the second communication module520 may be referred to as the “second device.”

The first communication module 510 includes a power-save module 505. Thepower-save module may control the first device entering and exiting apower-save mode. For example, the power-save module 505 mayautomatically place the first device into a sleep state of a power-savemode when the power-save module 505 detects no user interaction with thefirst device for a period of time. Also for example, the power-savemodule 505 may automatically place the first device into a wake state ofa power-save mode periodically based on the timeout of a wake-up timer.Alternatively, the power-save module 505 may place the first device inthe wake state when the module 505 detects an attempt at userinteraction with the first device. Accordingly, the scope of variousaspects of the present invention should not be limited to particularcharacteristics and implementations of power-save functionality.

The first communication module 510 includes a transceiver module 515.The transceiver module 515 may communicate with various network devicesover a variety of communication links. For example and withoutlimitation, the transceiver module 515 may communicate with anothernetworked device over a wired link, wireless link, electrical link,radio frequency link, tethered optical link, or non-tethered opticallink. Accordingly, the scope of various aspects of the present inventionshould not be limited by characteristics of a particular type oftransceiver or communication link.

The first communication module 510 includes a medium access control(MAC) module 520. The exemplary MAC module 520 is communicativelycoupled to the power-save module 505 and the transceiver module 515. Thegeneral function of the MAC module 520 is to control access to andcontrol the network communication medium. Such access may include, forexample, acquiring access and control of a channel of the communicationmedium, such as a time slot of a communication medium governed by TDMA,a frequency of a communication medium governed by FDM, a frequencyhopping sequence, or a code of a communication medium governed by CDMA.To this end, the MAC module 520 includes a medium access module 522 thatperforms communication medium access functionality. Alternatively,acquiring access to and control of the network communication medium mayinclude, for example, gaining access to and control of a plurality ofcommunication channels or all of the communication channels.

For example, the medium access module 522 may utilize the transceivermodule 515 to acquire access and control of a communication medium byutilizing any of a variety of communication medium access protocols. Forexample and without limitation, the medium access module 522 may acquiremedium access and control according to a carrier sense multiple accesswith collision avoidance (CSMA/CA) protocol. Alternatively, the mediumaccess module 522 may, for example, acquire access to the communicationmedium according to an ALOHA or a CSMA/CD protocol. Accordingly, thescope of various aspects of the present invention should not be limitedto characteristics of a particular medium access protocol.

The exemplary MAC module 520 also includes a communication mediumcontrol-passing module 521. After the medium access module 522 hasgained access and control of the communication medium, thecontrol-passing module 521 may pass control of the communication mediumto another networked device. Such a networked device may, for example,include a second networked device utilizing the second communicationmodule 540 (the “second device). After the second device receivescontrol of the communication medium from the first device, the seconddevice may then utilize the communication medium without having toperform various medium access activities, such as, for example,contending with other network devices for access and control of thecommunication medium.

The exemplary MAC module 520 may also communicate to various networkdevices that the first device has the capability to enter and exit asleep state of a power-save mode. Other network devices may then utilizethis information to govern their treatment of and communication with thefirst device.

Note that the MAC module 520 may incorporate various safeguardsgenerally associated with medium access, including for example, timeoutfunctions to ensure fair access to the communication medium for allnetwork devices. Thus, the MAC module 520 may include various aspects toensure that the first device may not control the communication mediumfor an inappropriate amount of time.

The control-passing module 521 may pass control of the communicationmedium to another networked device in a variety of ways. For example,the control-passing module 521 may utilize the transceiver module 515 tocommunicate an explicit message to another device transferring controlof the communication medium to the other device. Alternatively, forexample, the control-passing module 521 may utilize the transceivermodule 515 to communicate a null data frame to another device, thussignifying that the first device is no longer utilizing thecommunication medium and that the other device may then take control ofthe communication medium.

The first communication module 520 also includes a data communicationmodule 530 that is coupled to the MAC module 520, the transceiver module515 and the power-save module 505. After the MAC module 520 gains accessto and control of a communication medium, the data communication module530 may utilize the transceiver module 515 to communicate information toanother networked device. For example, in the illustrative system 500shown in FIG. 5, the data communication module 530 may utilize thetransceiver module 515 to communicate with the second device. The datacommunication module 530 may, for example, utilize the transceivermodule 515 to communicate a single packet or a stream of packets to thesecond device.

The data communication module 530 may also perform various datareceiving functions. For example, following transfer of control of thecommunication from the first device to the second device, the datacommunication module 530 may utilize the transceiver module 515 toreceive information communicated to the first device from the seconddevice, which now has control of the communication medium. Suchinformation may, for example, be in the form of a single data packet ora stream of data packets.

Further, the data communication module 530 may communicate with thepower-save module 505 to indicate to the power-save module 505 whencommunication between the first device and the second device iscomplete, thereby allowing the power-save module 505 to decide whetherto cause the first device to enter a sleep state of a power-save mode.

Various modules of the first communication module 510 may, for example,be incorporated into a single integrated circuit. Various modules mayinclude hardware, software, or combinations thereof. Various modules mayalso share components of the communication module 510, such as, forexample, a microprocessor, memory devices, bus infrastructure, clocks,etc. Accordingly, the scope of various aspects of the present inventionshould not be limited to particular arrangements and implementations ofthe various modules discussed.

Though not illustrated in FIG. 5, the first communication module 510 mayalso include various user interface modules, which may, for example,indicate to the user whether the device is in a power-save mode. Thevarious user interface modules may also indicate to a user that thedevice has recently received updated information. Such modules mayprovide the user with the ability to tailor user interface interactionwith the device in the manner best suited to the individual user.Accordingly, the scope of various aspects of the present inventionshould by no means be limited to various user interface modes, functionsor features.

The second communication module 540 is illustrated connected to a wiredLAN 544 through a wired LAN module 542. The second communication module540 may, for example, be utilized in a network access point device.However, the scope of various aspects of the present invention shouldnot be limited to a particular type of network device.

The second communication module 540 includes a transceiver module 550.The transceiver module 550 may communicate with various network devicesover a variety of communication links. For example and withoutlimitation, the transceiver module 515 may communicate with anothernetworked device over a wired link, wireless link, electrical link,radio frequency link, tethered optical link, or non-tethered opticallink. Accordingly, the scope of various aspects of the present inventionshould not be limited by characteristics of a particular type oftransceiver or communication link.

The second communication module 540 also includes a MAC module 560,which is communicatively coupled to the transceiver module 550. Similarto the MAC module 520 discussed previously with respect to the firstcommunication module 510, the exemplary MAC module 560 includes a mediumaccess module 562. The medium access module 562 may, for example, sharevarious aspects with the medium access module 522 discussed with regardto the first communication module 510.

The MAC module 560 also includes a control-passing module 564. Thecontrol-passing module 564 may utilize the transceiver module 550 toreceive a message from the first device passing control of thecommunication medium from the first device to the second device. Havingacquired control of the communication medium in this manner, the MACmodule 560 may access and control the communication medium withouthaving to perform various medium access activities. For example, ifaccess to the communication medium is generally governed by acontention-based medium access protocol, such as, for example, CSMA/CA,the MAC module 560 may acquire control directly from the first device,thereby by-passing the need to contend with other network devices foraccess to the communication medium.

The second communication module 540 also includes a data communicationmodule 580 that is communicatively coupled to the transceiver module 550and the MAC module 560. The data communication module 580 may, forexample, utilize the transceiver module 550 to receive information fromnetworked devices. The data communication module 580 may also, forexample, utilize the transceiver module 550 to communicate informationto other networked devices.

For example, prior to the MAC module 560 gaining control of thecommunication medium from the first device passing control of thecommunication medium to the second device, the data communication module580 may utilize the transceiver module 550 to receive information fromthe first device. Such information may include data and/or controlinformation, and may also include a medium access hand-off message. Sucha medium access hand-off message may also, for example, be a stand-alonemessage.

Also for example, subsequent to the MAC module 560 gaining control ofthe communication medium from the first device passing control of thecommunication medium to the second device, the data communication module580 may utilize the transceiver module 550 to communicate informationback to the first device. In the illustrative example of the seconddevice being a network access point device, the access point device mayhave been storing information destined for the first device in a bufferand awaiting instructions from the first device or an indication thatthe first device is not in a sleep state of a power-save mode.

The data communication module 580 is shown communicatively coupled to amessage buffer 590, in which may be stored information destined for thefirst device. The data communication module 580 may retrieve suchinformation from the message buffer 590 and utilize the transceivermodule 550 to communicate the information to the first device. The datacommunication module 580 may, for example, communicate such informationto the first device by communicating a single data packet or a stream ofdata packets to the first device, while the MAC module 560 maintainscontrol of the communication medium. Note that the message buffer 590may be incorporated into the second communication module 540 or not. Forexample, the message buffer 590 may be at another location accessible onthe wired LAN 544.

The second communication module 540 includes a power-save devicedatabase module 570, which is communicatively coupled to the power-savedetermination module 566 of the MAC module 560. The power-savedetermination module 566 (e.g., in coordination with the control-passingmodule 564) may utilize the information in the power-save devicedatabase module 570 to determine if a received medium control hand-offmessage was transmitted by a network device with power-save capability.For example, the second communication module 540 may respond to such amessage differently depending on the message source. For example, thesecond communication module 540 may decide not to accept control of thecommunication medium in response to messages received from networkeddevices that do not have power-save capability. Conversely, the secondcommunication module 540 may, for example, always accept control of thecommunication medium in response to medium control hand-off messagesreceived from networked devices that are power-save devices.

Various modules of the second communication module 540 may, for example,be incorporated into a single integrated circuit. Various modules mayinclude hardware, software, or combinations of hardware and software.Various modules may also share components of the second communicationmodule 540, such as, for example, a microprocessor, memory devices, businfrastructure, clocks, etc. Accordingly, the scope of various aspectsof the present invention should not be limited to particulararrangements and implementations of the various modules discussed.

FIG. 6 shows a flow diagram of a method 600 for controlling access to acommunication medium in accordance with various aspects of the presentinvention. The exemplary method 600 is presented in the context of acommunication network having a networked device with power-savecapability. However, the scope of various aspects of the presentinvention should, by no means, be limited to characteristics of suchpower-save devices or a network having such devices. Additionally, theexemplary method 600 may incorporate various aspects of the exemplarymethods 100, 200 shown in FIGS. 1 and 1 and discussed previously.

The method 600, at step 610, includes a first networked device exiting asleep state of a power-save mode. The first networked device may exitthe sleep state of the power-save mode for a variety of reasons,including but not limited to, user activity or timer activity. In analternative scenario, for example, the first networked device maycomplete some other activity with which it was pre-occupied.

The method 600, at step 620, then includes the first networked devicegaining access to and control of the network communications medium. Asdiscussed previously such access and control may, for example,correspond to one or more channel, frequency, timeslot, frequencyhopping pattern, or code. The first networked device may, for example,utilize a contention-based medium access protocol (e.g., CSMA/CA) togain access to the communication medium.

The method 600, at step 630, includes the first networked deviceutilizing the communication medium to communicate information to asecond networked device. The second networked device may be, forexample, an access point device in a wireless network. Alternatively,the second networked device may be, for example, a peer device.Accordingly, the scope of various aspects of the present inventionshould, by no means, be limited to characteristics of particular devicesor networks.

Step 630 may include the first networked device communicatinginformation to the second networked device in a data packet or aplurality of data packets. In an exemplary scenario, where afteracquiring access to and control of the communication medium at step 620,the first networked device has no information to communicate to thesecond networked device, the first networked device may by-pass step630.

The method 600, at step 640, includes passing control of thecommunication medium from the first networked device to a secondnetworked device. The second networked device may, for example, be thesame networked device to which the first networked device communicatedinformation in step 630. The second networked device, having therebygained control of the communication medium, may then utilize thecommunication medium without having to follow the medium access protocolgenerally governing access to the communication medium. For example andwithout limitation, in a scenario where access to the communicationmedium is generally governed by a contention-based medium access controlprotocol (e.g., CSMA/CA), the second networked device may utilize thecommunication medium without having to contend with other networkeddevices for access to the communication medium.

Step 640 is illustrated having two exemplary sub-steps. Step 642includes the first networked device communicating a medium controlhand-off message to the second networked device. The medium controlhand-off message may, for example, notify the second networked devicethat the second networked device may have control over the communicationmedium. The medium control hand-off message may have a variety of forms.For example, the hand-off message may be a stand-alone message or may bea flag in a multi-purpose message. For example, the hand-off message maybe a flag in a packet containing data and/or control information, whichmay be set to indicate to the receiving device that the sending devicehas no data or no more data to send.

Step 644 includes the second networked device, which received thehand-off message, verifying that the first networked device is apower-save device. In the exemplary method 600, the second networkeddevice may distinguish between power-save and non-power-save devices.For example, the second networked device may only accept a mediumcontrol hand-off from a power-save device and not from a non-power-savedevice. Note that allowing hand-off from a power-save device and notallowing hand-off from a non-power-save device is an exemplary scenarioand should, by no means, limit the scope of various aspects of thepresent invention.

Step 644 may include, for example, the second networked device analyzingmessages from the first networked device to determine whether the firstnetworked device is a power-save device. Alternatively, the secondnetworked device may access a database of known power-save devices todetermine if the first networked device is a power-save device. Thesecond networked device may perform such verification in a variety ofways, and the scope of various aspects of the present invention shouldnot be limited by characteristics of particular verification mechanisms.

The method 600, at step 650, includes the second networked device,having acquired control over the communication medium at step 640,utilizing the communication medium to communicate information. Forexample, the second networked device may communicate information back tothe first networked device.

In an exemplary power-save scenario, the second networked device mayhave stored traffic destined for the first networked device in a buffer,waiting for an indication that the first networked device is not in asleep state of a power-save mode. The second networked device may then,for example, having received an indication that the first networkeddevice is not in a sleep state of a power-save mode, and having justreceived control of the communication medium from the first networkeddevice, retrieve such stored information from the buffer and utilize thecommunication medium to communicate the retrieved information to thefirst networked device.

Step 650 may include, for example, communicating information to thefirst networked device, or other networked device, using a single packetor a stream of packets. Step 650 may include communicating suchinformation over the communication medium while maintaining control overthe communication medium. The method 600 thereby provides a mechanismwhereby a first and second networked device may communicate informationwith each other following only one successful acquisition of access toand control of the communication medium.

The method 600, at step 660, includes the second networked devicereleasing control of the communication medium. Step 660 may include, forexample, the second networked device communicating a message explicitlyindicating that the second networked device is releasing control of thecommunication medium. Alternatively, for example, step 660 may includethe second networked device discontinuing its utilization of thecommunication medium. Accordingly, the scope of various aspects of thepresent invention should not be limited by characteristics of particularmechanisms for releasing control of the communication medium.

Note that the medium access control for the communication medium mayinclude safeguards to keep a networked entity or set of networkedentities from controlling the communication medium for an inappropriateperiod of time. For example, the medium access protocol may include anupper time limit on the time that a device or group of devices maymaintain uninterrupted control of the communication medium.

In summary, a system and method are provided for accessing, controllingand utilizing a communication medium in a network. While the inventionhas been described with reference to certain aspects and embodiments, itwill be understood by those skilled in the art that various changes maybe made and equivalents may be substituted without departing from thescope of the invention. In addition, many modifications may be made toadapt a particular situation or material to the teachings of theinvention without departing from its scope. Therefore, it is intendedthat the invention not be limited to the particular embodimentdisclosed, but that the invention will include all embodiments fallingwithin the scope of the appended claims.

1. In a networked device having the capability to enter and exit a sleepstate of a power-saving mode, a method for controlling access to acommunication medium, the method comprising: exiting the sleep state ofthe power-saving mode; acquiring control of the communication mediumutilizing a contention-based medium access protocol; and passing controlof the communication medium to a second networked device, whereby thesecond networked device may communicate a plurality of informationpackets to the networked device without having to utilize thecontention-based medium access protocol to access the communicationmedium.
 2. The method of claim 1, further comprising, prior to passingcontrol of the communication medium to the second networked device,communicating data to the second networked device.
 3. The method ofclaim 1, wherein passing control of the communication medium to thesecond networked device comprise communicating a message to the secondnetworked device indicating that the networked device is a capable ofpower-save operation.
 4. The method of claim 1, wherein passing controlof the communication medium to the second networked device comprisescommunicating a message to the second networked device indicating thatthe networked device has no data to communicate to the second networkeddevice.
 5. The method of claim 1, further comprising, after passingcontrol of the communication medium to the second networked device,receiving a plurality of information packets from the second networkeddevice transmitted over the communication medium while the secondnetworked device maintains control over the communication medium.
 6. Themethod of claim 1, further comprising, after passing control of thecommunication medium to the second networked device: receiving anindication from the second networked device that the second networkeddevice has no data to communicate to the networked device; and enteringa sleep state of a power-save mode.
 7. A communication module forutilization in a networked device, the networked device having thecapability to enter and exit a sleep state of a power-save mode, thecommunication module comprising: a transceiver module; a power-savemodule that controls the networked device entering and exiting apower-save mode; and a medium access control (MAC) modulecommunicatively coupled to the transceiver module and the power-savemodule, the medium access control module comprising: a first modulethat, after the power-save module causes the networked device to exitthe sleep state of the power-save mode, utilizes the transceiver moduleto acquire control of a network communication medium utilizing acontention-based medium access protocol; and a second module thatutilizes the transceiver module to transfer control of the communicationmedium to a second networked device, whereby the second networked devicemay communicate a plurality of information packets to the networkeddevice over the communication medium without having to utilize thecontention-based medium access protocol to access the communicationmedium.
 8. The communication module of claim 7, further comprising adata communication module communicatively coupled to the transceivermodule and the medium access control module, wherein the datacommunication module, prior to the second module transferring control ofthe communication medium to the second networked device, utilizes thetransceiver module to communicate information to the second networkeddevice.
 9. The communication module of claim 7, wherein the secondmodule transfers control of the communication medium to the secondnetworked device by utilizing the transceiver module to communicate amessage to the second networked device indicating that the networkeddevice has no data to communicate to the second networked device. 10.The communication module of claim 7, further comprising a datacommunication module communicatively coupled to the transceiver moduleand the medium access module, wherein the data communication module,after the second module transfers control of the communication medium tothe second networked device, utilizes the transceiver module to receivea plurality of information packets from the second networked device thatis communicated over the communication medium while the second networkeddevice maintains control over the communication medium.
 11. Thecommunication module of claim 7, further comprising a data communicationmodule communicatively coupled to the transceiver module and the mediumaccess module, wherein the power-save module, after the datacommunication module receives an indication that the second networkeddevice has no data to communicate to the networked device, causes thenetworked device to enter a sleep state of a power-save mode.
 12. Thecommunication module of claim 7, wherein the transceiver module,power-save module, and MAC module are integrated in a single integratedcircuit.
 13. In a networked device having the capability to communicatewith a second networked device over a communication medium, the secondnetworked device having gained control over the communication medium byutilizing a contention-based medium access protocol after exiting from asleep state of a power-save mode, a method for controlling access to acommunication medium, the method comprising: receiving a message fromthe second networked device that passes control of the communicationmedium to the networked device, whereby the networked device maycommunicate a plurality of information packets to the second networkeddevice without having to utilize the contention-based medium accessprotocol to access the communication medium; and communicatinginformation to the second networked device while maintaining controlover the communication medium.
 14. The method of claim 13, whereincommunicating information to the second networked device comprisescommunicating a plurality of information packets to the second networkeddevice while maintaining control over the communication medium.
 15. Themethod of claim 13, further comprising determining if the networkeddevice is a device having the capability to enter and exit a sleep stateof a power-save mode.
 16. The method of claim 15, wherein the networkeddevice does not perform the step of communicating information to thesecond networked device while maintaining control over the communicationmedium if the networked device determines that the second networkeddevice is not a device having the capability to enter and exit a sleepstate of a power-save mode.
 17. The method of claim 13, wherein themessage from the second networked device that passes control of thecommunication medium to the network device comprises data informationand control information.
 18. A communication module for utilization in anetworked device having the capability to communicate with a secondnetworked device over a communication medium, the second networkeddevice having gained control of the communication medium utilizing acontention-based medium access protocol after exiting from a sleep stateof a power-save mode, the communication module comprising: a transceivermodule; a medium access control (MAC) module communicatively coupled tothe transceiver module, wherein the MAC module utilizes the transceivermodule to receive a medium control passing message from the secondnetworked device, after which the MAC module may take control of thecommunication medium for communicating a plurality of informationpackets to the second networked device without utilizing thecontention-based medium access protocol; and a data communication modulecommunicatively coupled to the transceiver module and the MAC modulethat utilizes the transceiver module to communicate information to thesecond networked device while maintaining control of the communicationmedium.
 19. The communication module of claim 18, wherein the datacommunication module utilizes the transceiver module to communicateinformation to the second networked device in a plurality of datapackets while maintaining control of the communication medium.
 20. Thecommunication module of claim 18, wherein the MAC module comprises afirst module that determines if the second networked device is apower-save device.
 21. The communication module of claim 20, furthercomprising a database module coupled to the MAC module that comprises alist of network devices having power-save capability, wherein the MACmodule accesses the database module to determine of the second networkeddevice is a power-save device.
 22. The communication module of claim 20,wherein the data communication module does not utilize the transceivermodule to communicate information to the second networked device whilemaintaining control of the communication medium if the first moduledetermines that the second networked device is not a power-save device.23. The communication module of claim 18, wherein the medium controlpassing message from the second networked device comprises datainformation and control information.
 24. The communication module ofclaim 18, wherein the transceiver module, MAC module and datacommunication module are all integrated in a single integrated circuit.25. A method for controlling access to a communication medium in acommunication network, the method comprising: exiting a sleep state of apower-save mode by a first networked device; acquiring control of thecommunication medium by the first networked device utilizing acontention-based medium access protocol; passing control of thecommunication medium from the first networked device to a secondnetworked device, whereby the second networked device may communicate aplurality of information packets to the first networked device over thecommunication medium without having to utilize the contention-basedmedium access protocol to access the communication medium.
 26. Themethod of claim 25, wherein passing control of the communication mediumcomprises verifying at the second networked device that the firstnetworked device is a device capable of power-save operation.
 27. Themethod of claim 25, further comprising releasing control of thecommunication medium by the second networked device, such thatsubsequent access of the communication medium is governed by thecontention-based medium access protocol.
 28. The method of claim 25,wherein passing control of the communication medium comprisescommunicating a message from the first networked device to the secondnetworked device over the communication medium, the message containingdata and control information.
 29. The method of claim 25, furthercomprising, after passing control of the communication medium to thesecond networked device, communicating a plurality of data packets fromthe second networked device to the first networked device while thesecond networked device retains control over the communication medium.